Harnessing polydiacetylene (PDA): A review of structural mechanics and infectious disease detection

Abstract

Polydiacetylenes (PDAs) are intriguing polymers distinguished by their unique ene-yne alternating backbone arising from the 1,4-addition of diacetylenes under UV irradiation. The remarkable thing about this polymerization process is that it does not require solvents, catalysts, or initiators. However, PDAs are unique due to their exceptional responsiveness to stimuli. When exposed to stimulus from outside sources, PDAs undergo a distinctive blue-to-red colour transition accompanied by a fluorescence turn-on, making them ideal candidates for sensing applications. This photophysical transformation, triggered by environmental changes, facilitates direct visual detection with the naked eye or via spectrometry. By functionalizing the hydrophilic head groups, PDA's sensing capabilities are enhanced, enabling label-free detection of viruses, bacteria, proteins, and other biomolecules. PDA biosensors can be crucial in detecting various infectious diseases caused by viruses and bacteria. PDA biosensors leverage photonic crystal structures' sensitive and specific optical properties to detect target molecules such as viral antigens or bacterial biomarkers. These biosensors can also be functionalized with particular capture agents, such as antibodies or nucleic acid probes, to selectively bind and detect the target analytes. Despite extensive research into PDA materials and their applications, ongoing advancements continue to broaden their potential. This review consolidates recent progress in PDA-based biosensors and their mechanisms, shedding light on molecular properties, characterization, and matrix selection of PDA vesicles. The review also focuses on the status of PDA vesicles for infectious disease detection.